Error F9 in Fagor boiler

Error F9 in Fagor boiler

Description

Error: F9

The F9 fault in a Fagor boiler is related to detection of the flame and the behaviour of the primary circuit temperature control. It may not always appear clearly on the display, which can make diagnosis harder. Below is a concise explanation of how it acts and what to check.

Causes

• Incorrect flame detection or intermittent flame.
• Faulty primary circuit temperature sensor (thermistor).
• Primary circuit output temperature below required threshold (thermistor < 50ºC) while the burner is demanding high power (>95%) for an extended period (more than 5 minutes).
• Control electronics responding to the mismatch between demand and measured temperature.

What the boiler does (symptoms)

If the control detects a malfunction (for example, a thermistor reading below 50ºC while the burner is running at very high power for over 5 minutes), the boiler can perform a sequence of shutdowns and re-ignitions as it attempts to correct the condition. This cycling and the unclear display of the fault are why users may find the problem difficult to detect.

Basic checks and solutions

1. Verify presence and stability of the flame during operation.
2. Check the primary circuit temperature sensor (thermistor) and its wiring for proper connection and obvious damage.
3. Measure the primary circuit output temperature; ensure it reaches and maintains a temperature above approximately 50ºC under normal operating conditions.
4. Inspect for causes that could prevent the system from raising temperature despite high burner output (circulation issues, blocked heat exchanger, pump faults, air in the system, valves closed).
5. If the system repeatedly reaches high burner power (>95%) without the expected temperature rise and the unit cycles, avoid repeatedly attempting resets; note the exact behaviour and fault timing for the technician.

When to call a technician

If you cannot identify or fix the problem, contact Fagor technical service or a qualified heating engineer. They can perform detailed diagnostics (checking the thermistor, control board, gas supply, flame sensor and hydraulic circuit) and repair safely and efficiently.

Error F9 in Fagor kitchen hob (note)

Description

Error: F9

On Fagor kitchen hobs, the F9 code means a different issue: generator (plate) overheating, usually caused by poor ventilation or an overheating element.

Causes

• Short or inadequate ventilation around the hob.
• Thermostat or control sensor on the large cooking zone malfunctioning.
• Excessive local heat buildup from prolonged heavy use without cooling breaks.

Solution and tips

• Often the F9 warning will clear automatically once the hob cools down and ventilation improves.
• If the code persists, check ventilation around the hob and ensure cooling paths are not blocked.
• Inspect or have a technician check the thermostat/sensor for the large cooking zone that controls temperature.
• If you cannot clear the error or the hob continues to overheat, contact technical service to diagnose and repair.

More tips

If the error persists on either appliance, avoid prolonged attempts to reset the unit. Note the exact conditions when the fault appears (temperature, operating mode, time) and provide this information to the technician to speed up diagnosis and repair.

Other error codes

For other Fagor boiler or hob error codes, consult the appliance documentation or the manufacturer’s fault code list for device-specific meanings and recommended actions.